Assessment Status Notes

Data Deficient (DD).

Very few collections reported for this species but Psathyrella is understudied and P. cystidiosa requires microscopic examination to separate from similar species.

Taxonomic notes

Psathyrella cystidiosa is a cryptic species. It is difficult to recognize in the field. The cap can grow up to 30 mm broad. It has concentric zones of color from light yellowish brown at the center to deep yellowish brown towards the edge. The white stalk is 16-50 mm long and 1-3 mm wide. It has a dark grayish brown spore print. Microscopically this species can be distinguished from other similar looking species by its thick-walled cystidia, a sterile structure found on the face of the gills. Psathyrella cystidiosa is most similar to P. olympiana both microscopically and macroscopically, but can be separated statistically by measuring the apical wall of the cystidia: the wall at the apex of the cystidia is thicker in P. cystidiosa (Padamsee 2001).

Why suggested for a Global Red List Assessment?

Psathyrella cystidiosa was listed as an endangered species in Minnesota in 1996, previously thought to be endemic to Minnesota. Psathyrella cystidiosa is a cryptic and very rarely reported mushroom, with specimens in the USA from 3 states, at a total of 5 sites. This is clearly an under-reported species because careful microscopic observation is required for identification.

Geographic range

Three states of USA. Known from 3 sites in Minnesota. There is a tentative collection in central Illinois and one in Tennessee.

Population and Trends

First described in 1912 from Minnesota. Collected in 1948 in Tennessee (collection by L. R. Hesler on Mycoportal.org). Searched for specifically and then found in 2 new counties in Minnesota, 1998, 1999, 2000. There is a tentative collection in 2002 from central Illinois (Kuo 2011).

Population Trend: Uncertain

Habitat and Ecology

The original description of P. cystidiosa mentioned only that it had been found with a ball of soil attached to the base. The two recent collections in Minnesota were found on the ground and also scattered along a dead branch on the ground. Both were found in deciduous forests. The mushroom occurs in shade and may have a preference for thoroughly moistened areas prior to fruiting.
Not much is known about the biology of P. cystidiosa. It is a saprotroph and is usually found in small groups or scattered. The species is found in moist soil or attached to dead branches of deciduous trees. A search for this mushroom in the same location conducted one year after the specimens were found (McLaughlin 1999) did not find this species, but it was discovered at a different location during that same year, indicating that P. cystidiosa may not fruit every year. This species is likely dispersed in the form of mycelia (thread-like structures that make up the body of a fungus) and spores. Low nutrient availability probably triggers the growth of the mushroom in this species. The earliest documentation of this species is the 12th of June and the latest is the 12th of August. Because this species has only been reported a few times from two states, it is difficult to specify its life history. Further studies about P. cystidiosa should reveal more information about its biology.

ForestTemperate Forest

Threats

Threats would include loss of suitable habitat and substrates by development and soil disturbance.

Conservation Actions

Psathyrella cystidiosa seems to prefer moist soil, but the soil does not need to be continuously wet. It is found in soil or attached to dead branches, thus removal of dead wood from the forest floor would likely threaten this species. This species was also found among relatively immature trees.

Site/area protectionSite/area managementAwareness & communications

Research needed

Psathyrella cystidiosa is rare mushroom in the USA, described from Minnesota and also collected in Tennessee and possibly Illinois. It was first found in Minneapolis, Hennepin County, in 1912, but was not collected again until 1998 when it was found as part of a DNR-sponsored mushroom survey (McLaughlin 1998). So far, collections have been made during 1998, 1999, 2000 in Rice and Washington counties, although specimens have only been found two or three times in each county and only in small groups.
For Minnesota surveys looking for Psathyrella, twenty collecting trips have resulted in two collections of P. cystidiosa. Four counties have been examined with focused searches in Nerstrand Woods State Park, Afton State Park, Wolsfeld Woods Scientific and Natural Area, Belwyn Educational Center, and the Minnesota Valley National Wildlife Refuge. Extensive research has been conducted on the separation of P. cystidiosa from P. olympiana (Padamsee 2001; Padamsee et al. 2008).
Based on previous collections, the best time to search for this mushroom in Minnesota is from early June through mid-August. Careful collecting of Psathyrella and microscopic work is needed to document its distribution in eastern North America.